1. Field of the Invention
This invention relates to elastomeric fibers, to fabrics made from such fibers that are useful in cardiovascular prosthesis, and more particularly to an elastomeric composite material comprising an artificial core fiber and an elastomeric polypeptide chemically bonded to the surface of the core fiber or appropriately interwoven with it.
2. Description of the Prior Art
Replacement of a blood vessel by a posthetic device is an important and common practice in modern vascular surgery. Although some use is made of veins or arteries taken from other portions of a patient's body, most of such prosthetic devices are prepared from artificial materials that can be prepared in a variety of sizes and stored in a sterile state ready for use.
There are several essential properties of cardiovascular prosthetic materials, among which are the following:
1. Retardation of thrombosis and thromboembolism (antithrombogenic);
2. Minimal harm to blood cells and minimal blood cell adhesion;
3. Long life as prosthetic inserts; and
4. Close mimicry of the physical and chemical properties of natural blood vessel such as similar elastic modulus and tensile strength.
Another useful property would be a chemotaxis that induced rapid endothelialization and invasion of connective tissue cells for vascular wall reconstruction in a manner such that the prosthesis would be slowly replaced by and integrated into newly synthesized internal elastic lamina. None of the materials presently being used can fulfill all of these requirements.
The most commonly used fabric for blood vessel prosthesis is made from Dacron (Trademark, DuPont), a synthetic polyester fiber made from polyethylene terephthalate. Dacron has been used in several weaves and in combination with other materials. An example of a frequently used material is the DeBakey Elastic Dacron fabric manufactured by USCI, a division of C. R. Bard, Inc. (Cat. No. 007830). Other commonly used materials are felted polyurethane and polytetrafluorethylene (Berkowitz et al., Surgery, 72, 221 (1972); Wagner et al., J. Surg. Res., 1, 53 (1956); Goldfarb et al., Trans. Am. Soc. Art. Int. Org., XXIII, 268 (1977)).
However, none of these materials, even when specially woven or crimped, mimics the elastic nature of natural blood vessel walls (Takabayashi et al., J. Surg. Res., 19, 209 (1975)). Because of this, blood pressure response and blood flow occur differently in natural and artificial blood vessels, and the desirable normal flow characteristics and pressure response are not attained. Changes in blood flow are undesirable and often lead to clotting. A material that more closely mimics the natural elastic behavior of blood vessels is still needed.